The Experimental Study On Cu Polishing Slurries In The IC Process

Chemical mechanical polishing process (CMP) is the most effective method which is currently used to implement local and global material planarization,and it is widely applied in flattened surface treatment of hard brittle materials and IC process.Copper is already used as middle lead of copper ULSI,all nations research intensify on main process of copper CMP which is used for processing miniaturedevice.Slurries are key factors of affecting global planarization of copper CMP,which decides the stand or fall of polishing process.Alkaline slurry has some advantages,such as little corrosive,high selectivity (forming automatically a layer of oxide film in the copper surfaces to enhance selectivity) etc.Domestic research level has developed a lot,but there is a big gap compared with international famous companies. Therefore,the alkaline slurry study which is suitable for sub-micron and deep submicron process is necessary.In the alkaline slurries,arasive,oxidant,pH regulator and complexing agent are the main components,and they almostly determine material removal rate and surface quality in the CMP process.The paper used a new CMP method,which was the method of fine atomization CMP.The method is that the components are atomized with controlling ultrasound frequency to form SMD5-15um uniform droplets,and then it is transported to the polishing interface.They can form uniform film which has low shear strength on the surface of workpiece through the strong adsorption and the high-performance uniform chemistry between interface,and then the film is removed by mechanical function.The method can significantly reduce the dosage of slurry,and it is helpful in getting better workpiece surface quality.Therefore,there is far-reaching significance in researching the polishing slurry which is suitable to fine atomization CMP.This paper located in alkaline copper slurries research, through the analysis of the copper CMP mechanism, main factors that influenced traditional polishing and atomization effect have been found out.The single factor choice experiments of components were carried out in the UNIPOL1502 lapping polishing machine, abrasive, organic alkali and antioxidant and other major components were selected,these ingredients are suitable for IC copper interconnection layer process with traditional polishing and fine atomization polishing.In this paper optimization experiments of components were carried out to select the optimal for the copper slurries.Lastly, optimization experiments of blending polishing components and process parameters have been done, and finally got good atomizing slurry which is suitable for the IC process ,and finally got good atomizing slurry which is suitable for the IC process. After polishing,the atomization CMP method could obtain higher surface planeness of the copper like the traditional CMP, but the consumption dosage of polishing slurry in atomization CMP was dozens of times less than that in the traditional polishing.In the traditional CMP process,slurry flowed to the polishing pad at a certain rate,but special slurries were imported into the polishing pad through the way of ultrasound fine atomization in my subject,therefore, slurry's usage was greatly declined,polishing efficiency was improved,so that the cost of IC production reduces greatly in the CMP stage, and their products'competitiveness are enhanced,the way of fine atomization CMP is helpful to direct the IC industry to green environmental development.Because ultrasonic atomization polishing is a kind of new proposed polishing method,so the research is still in the foundation stage temporarily,the experimental results is also initial success,But its little dosage and environmental protection have great significance,especially to the ultra precision smooth chip surface of future hard and brittle materials has important practical significance.In this paper,new CMP process of ultrasonic fine atomization was used to polish pieces of copper,which concluded that the maximum material removal rate was 188 nm/min,the optimal precision of polishing copper surface was 3.81 nm.